1. Field of the Invention
This invention relates to linear, branched, and/or cross-linked urethane-coupled block polymers of quinone-coupled polyphenylene oxides. The polymers are prepared by contacting polyfunctional isocyanates with quinone-coupled polyphenylene oxides having an average hydroxyl group per molecule value greater than zero including 2.0 or less.
2. Description of the Prior Art
Self-condensation reactions of certain phenols employing oxygen in combination with an effective oxidative coupling catalyst system to form prior art polyphenylene oxides, i.e., polyphenylene oxides having an average hydroxyl group per molecule of 1.0 or less, are described in various U.S. patent applications including Hay's U.S. Pat. Nos. 3,306,879; 3,914,266; 4,028,341, a continuation-in-part of Ser. No. 441,295, filed Feb. 11, 1974, now abandoned; and Olander's U.S. Pat. Nos. 3,956,442; 3,965,069; 3,972,851 and 4,054,553.
Block polymers of prior art polyphenylene oxides employing simple bifunctional coupling compounds such as diacyl halides, diisocyanates, bis(haloaryl)sulfones, etc., are described in White's U.S. Pat. Nos. 3,793,564; 3,770,850; 3,809,729 and 3,875,256.